In recent years, a decrease in size and weight, an increase in power output and an increase in efficiency have been required in a permanent magnet motor used in a hybrid car, a hard disk drive, or the like. To realize such a decrease in size and weight, an increase in power output and an increase in efficiency in the permanent magnet motor mentioned above, film-thinning and a further improvement in magnetic performance have been required of a permanent magnet to be embedded in the permanent magnet motor.
As a method for manufacturing a permanent magnet, for instance, a powder sintering process may be used. In this powder sintering process, first, raw material is coarsely milled and then finely milled into magnet powder by a jet mill (dry-milling method) or a wet bead mill (wet-milling method). Thereafter, the magnet powder is put in a die and pressed to form into a desired shape with a magnetic field applied from outside. Then, the magnet powder formed into the desired shape and solidified is sintered at a predetermined temperature (for instance, at a temperature between 800 and 1150 degrees Celsius for the case of Nd—Fe—B-based magnet) for completion (See, for instance, Japanese Laid-open Patent Application Publication No. 2-266503).